LAREDO - U.S. Border Patrol agent Juan David Ortiz carried out the murders of four women he targeted in a "cold and callous way," Webb County District Attorney Isidro R. “Chilo” Alaniz said.

"There was common scheme ... there was a certain community or a group of people that he was seeking out," Alaniz told a crowded room of reporters at a news conference Monday at the Webb County Sheriff's Office.

"Unfortunately, this is a community of people that are vulnerable, whether it be because of alcohol, substance abuse, drug addiction or prostitution," he continued.

The arrest of a veteran Border Patrol agent as a serial murder suspect in the shooting deaths of four women occurred Saturday in the border community.

Ortiz, a 10-year veteran of U.S. Customs and Border Protection, was being held on four counts of murder, as well as one count each of evading arrest or detention, unlawful restraint — expose to serious bodily injury, and aggravated assault with a deadly weapon, according to online jail records.

The Laredo home of 35-year-old Juan David Ortiz is pictured in center. Ortiz, a 10-year-veteran of U.S. Customs and Border Protection, was arrested Sept. 15 for the murder of four women.(Photo: Eleanor Dearman/Caller-Times)

His bond was set at $2.5 million. Alaniz said prosecutors have not yet decided if the case will be upgraded to capital murder. He did not disclose a motive for the killings.

A representative from the Webb County Sheriff's office walked through the timeline surrounding the killings. He also identified one of the victims as Humberto Ortiz, 28.

The district attorney confirmed that the victim is a transgender woman; she identified herself on social media as Nikki Enriquez.

The fourth victim's name was not made public since family members had not yet been notified.

Police say they found the bodies of four people who had each been shot to death over a 10-day period.

On Sept. 3, Melissa Ramirez, 29, was killed after Juan David Ortiz picked her up on San Bernardo Avenue in Laredo. He drove to the city limits and shot her multiple times in the head, a criminal complaint states.

Authorities identified Claudine Ann Luera, 42, as another victim in the serial killing spree. Her body was discovered on a roadside by a truck driver on Sept. 13. She died at a local hospital later.

Claudine Anne Luera(Photo: Contributed photo)

Luera's niece said through social media her family has been hurt and offended by references from authorities and the media describing her aunt as a sex worker.

"She was a mother, a daughter, a sister, an aunt, a niece, a cousin, and a friend," wrote Karina Ramos in an emotional Facebook post on Monday. "Most of all SHE WAS LOVED. She was murdered by a monster who murdered 3 others, luckily the 5th woman got away."

"The fact that there’s a 'serial killer' in a small Texas town is big news, and the one thing all the articles mention is the victims were PROSTITUTES," writes Ramos. "As if that makes her less of a victim. As if that makes him less of a monster. As if she deserved what she got. As if it makes any difference at all. Her name was Claudine Anne Luera and let me repeat myself: SHE WAS LOVED."

Ramos said her aunt was the daughter of "a beautiful Scottish mother and grumpy Mexican father."

"She was the mother of 2 sets of twins and a hardworking, wonderful daughter," she said, noting two of Luera's children are autistic. "And we are a proud autism family full of love and support for them."

Ramos said her aunt struggled with her drug addiction, but "when she was winning her fight against drug abuse, she was a wonderful thriving mother."

"She held out as long as she could, but seemingly small bad decisions snowballed," said Ramos. "We don’t know why she fell off the wagon."

Through Luera's ups and downs, however, her large extended family never stopped loving her, said Ramos.

"We wished and prayed she’d overcome her demons and go back to who we knew she could be. But even when she lost everything because of her drug dependence, SHE WAS LOVED," Ramos wrote.

On Monday, Webb County Chief Deputy Federico Garza said Ortiz knew his victims.

“He had entrusted the victims to come along with him several times,” Garza said. “He entrusted them in that way. He knew the victims and the victims knew him. ”

Alaniz said the current evidence indicates the victims would engage in either drug use or were sex workers.

“There appears to be some history between Ortiz and this community,” Alaniz said. “That is what we’re looking at right now.”

The sheriff added that Ortiz had a “dislike for the community the victims represented.”

“He found himself in a situation that whatever anger he had inside of him, we don’t know yet,” Garza said.

Prior to Ortiz's arrest, authorities were already working under the suspicion that the first two deaths were connected, he said.

“We had an idea that there was a pattern in the murders, so we were identifying those things,” Garza said.

Garza said deputies got a break in the case when a fifth person, a woman, managed to escape from Ortiz near a gas station. The person told authorities that Ortiz began acting oddly when they had a conversation about Ramirez's death.

Investigators went to Ortiz's home but he was already gone. They arrested him early Saturday morning after SWAT team members found him hiding near a pickup truck at a nearby motel.